The most sure way of telling if all the principles of effective work with SuperMemo are satisfied is the user's pleasure experienced during repetitions. This is an infallible litmus test and should constantly be examined in order to detect the reasons for unsatisfactory progress. All problems mentioned earlier such as backlog of items, recall problems, monotonous repetitions, garbage knowledge, superficial items, tiredness, etc., are certain to take the gilt off the SuperMemo work and result in disillusionment.